itaps-parallel Part handle decision

[Carl Ollivier-Gooch]

Tim Tautges wrote:
> 
> 
> Devine, Karen D wrote:
>> All:
>>
>> Some questions arose about whether we had reached a consensus on how to
>> access part info.  I believe we did reach a consensus, but I have not yet
>> updated the interface document.  Please forgive me for the delay; this
>> summer has been just crazy!  I'll make the update a priority for our 
>> phone
>> conf.
>>
>> Summarizing the consensus:  Part handles exist to identify on-processor
>> parts; these part handles can be passed in place of entity sets to 
>> many of
>> the iMesh functions.  Global identification of parts is accomplished 
>> through
>> part IDs that are globally unique.  Functions that convert between 
>> part IDs
>> and part handles will return valid values for on-processor parts; for
>> off-processor parts, they will return errors.
> 
> Dare we say on-processor OR neighbor parts?

I don't see why we would want to.

Part handles are going to be used exclusively for local, on-process 
queries about parts, and global part ID's for stuff involving 
communication.  It doesn't make sense to have a part handle on another 
process --- you can't do anything with it but send it back to its owner, 
using some call that requires a global part ID.

If an implementation wants to deal with things differently than that 
below the interface level, that's fine, but at the interface level, my 
understanding was that we had agreed to effectively divide interface 
functions that refer to parts into those that are strictly local (which 
will take a part handle) and those that require communication (which 
will take a global part ID).  Yes, implementations will have to convert 
these things under the hood, but IMO that's a way better alternative 
than having two versions of all the communication functions (one taking 
a global ID, the other a process rank/part handle pair).

Carl

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